If the stain on the cloth was clearly from an area of the cloth that did not enter the vagina, you can attribute it to perineal bleeding, based on your irritation. This is assuming that you have a history of such irritation associated sometimes with bleeding.
If you are not sure, you could wipe the area of irritation to check for further bleeding. If you have further bleeding, or can identify an area of irritation, that could also be relied on here, as could medical confirmation on exam from your doctor or a bodeket taharah.
If you remain in doubt, please show your cloth to your rav.